FEVER 



679 



Normal 



surprise But in any case, no mere change in the absolute quantities 

 : heat formed and lost is sufficient to explain the febrile rise of 

 temperature; there must be a change in the relative proportion 

 1 hat an increase in heat-production is not of itself enough to produce 

 fever is proved by the fact that severe muscular work, which in- 

 creases the metabolism more than high fever, only causes in a 

 . healthy man a rise of about i C. in the rectal temperature. When 

 the work is over, the temperature comes rapidly back to normal. 

 t he essence of the change in fever is a derangement of the mechanism 

 by which in the healthy body excess or defect of average metab- 

 olism, or of average heat- 

 loss, is at once compensated 

 and the equilibrium of tem- 

 perature maintained. 



This derangement only lasts 

 as long as the temperature 

 is rising. When it becomes 

 stationary at its maximum 

 we have again adjustment, 

 again equality of production 

 and escape of heat; but the 

 adjustment is now pitched 

 for a higher scale of tempera- 

 ture. A rough analogy, so 

 far as one part of the process 

 is concerned, may be found 

 in the behaviour of the 

 ordinary gas-regulator of a 

 water-bath. It can be ' set ' 

 for any temperature. That 

 temperature, once reached, 

 remains constant within nar- 

 row limits of oscillation; but 

 the regulator can be equally 

 well adjusted for a higher or 

 a lower temperature. It is, 

 however, important to note that the equilibrium is more unstable 

 in fever than in health, so that changes of external temperature more 

 easily depress or increase the temperature of a fever patient than of 

 a healthy man. 



Rosenthal has concluded from calori metric observations that, in 

 the first stage of fever, while the temperature is rising, there is 

 always increased retention of heat. Maragliano actually found 

 evidence, by means of the plethysmograph, that the cutaneous 

 vessels are at this stage constricted, and that the constriction may 

 even precede the rise of temperature. The blood- flow in the feet 



mntrature. 



20u, nvrmttl I t 



He at Production.-* 

 footless 



Fig. 215. Diagram to show the Possible 

 Relations between Heat -Production and 

 Heat -Loss in Fever. 



